1. Field of the Invention
The present invention relates to a portable terminal unit having a foldable casing.
2. Description of the Related Art
Foldable portable telephones have appeared in the market. These portable telephones have a casing having two discrete pieces that can be folded/unfolded (opened/closed) at a hinge. A conventional portable telephone of this type has been disclosed in Japanese Patent Application Laid-open Publication Nos. 2002-320006 and H11-353283.
A display section is arranged in one of the pieces (upper lid) and an operation section is arranged in other piece (lower lid). An opening-closing detection switch detects change in state of the casing, i.e., change of folded to unfolded state or vice versa. Based on the change in the state of the casing, booting of applications is controlled. For example, a display is turned ON when the casing is opened, and the display is turned OFF when the casing is closed.
However, if the casing is opened/closed repeatedly, due to repeated operation of the opening-closing detection switch (chattering), the operation of the opening-closing detection switch becomes unstable.
Conventionally, timer is counted and detection of a change in state of the casing is performed only when a predetermined time elapses. The predetermined time for detection of change of state from open state to close state and vice versa is set same, moreover, it is set short so that the portable telephone can be operated almost at the same time as it is opened.